Possible Duplicate:
How to look up a symbol?

The instructor of a statistics and probability course uses an odd (to me) symbol for logical negation. The symbol is not a tide (~) or an exclamation mark (!) or the bar-over symbol. This symbol looks like the top right hand corner of a rectangle. What is this symbol called?

marked as duplicate by Werner, diabonas, lockstep, Count Zero, Caramdir Jul 23 '12 at 18:19

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • Welcome to TeX.sx! Could you upload a sketch of this symbol to help us identify it, please? As new user without image posting privileges simply include the image as normal and remove the ! in front of it to turn it into a link. A moderator or another user with edit privileges can then reinsert the ! to turn it into an image again. – diabonas Jul 23 '12 at 18:13
  • 6
    Also, have you already tried Detexify? – diabonas Jul 23 '12 at 18:14
  • 7
    You're looking for $\neg$; for more symbols, see How to look up a symbol? – Werner Jul 23 '12 at 18:14

I have seen that symbol rather frequently and is a popular mathematical notation. AFAIK ~ and ! are more popular in computer science/engineering, because there is an actual symbol for that on the keyboard. :) The symbol is defined in math mode as \neg.

  • 9
    As a character, it’s “¬” U+00AC NOT SIGN, and it’s the standard symbol for negation in logic and mathematics (most recently, as per the ISO 80000-2 standard, which does not even mention other notations for it). – Jukka K. Korpela Jul 23 '12 at 18:22
  • Actually UK keyboards have the ¬ symbol too. As does the US international keyboard layout (altgr + "\"). So the reason other symbols are more popular is because the normal US layout is more common. – jiggunjer Jun 21 '16 at 7:01

Not the answer you're looking for? Browse other questions tagged or ask your own question.